It is desirable to cause a controlled stimulation of individual nerves. U.S. Pat. No. 6,921,413 issued to Mahadevan-Jansen et al. on Jul. 26, 2005, and titled “METHODS AND DEVICES FOR OPTICAL STIMULATION OF NEURAL TISSUES,” is incorporated herein by reference. Mahadevan-Jansen et al. note that traditional methods of stimulation include electrical, mechanical, thermal, and chemical. A neuron will propagate an electrical impulse (a nerve action potential) in response to a stimulus. The most common form of applying such stimulation is to form a transient current or voltage pulse applied through electrodes. Electrical, mechanical, and chemical stimulations have many limitations. To name a few, stimulation by such methods typically results in non-specific stimulation of neurons and/or damage to neurons. Difficulty exists in recording electrical activity from the neuron due to an electrical artifact created by the stimulus. To stimulate only one or a few neurons, fragile micro-electrodes need to be fashioned and carefully inserted into the tissue to be stimulated. Such techniques do not easily lend themselves to implantable electrodes for long-term use in stimulation of neural tissue. Mahadevan-Jansen et al. describe the use of low-power light from a free-electron laser (FEL) for optically stimulating selected individual nerve cells in vivo, while at the same time not stimulating neighboring cells with the laser light. However, FELs are expensive, large, awkward and unwieldy.
Various patents have described lasers that emit in the infrared (e.g., U.S. Pat. No. 6,184,542 issued Feb. 6, 2001 to Gerard A. Alphonse; U.S. Pat. No. 6,301,279 issued Oct. 9, 2001 to Dmitri Z. Garbuzov, et al.; U.S. Pat. No. 6,339,606 issued Jan. 15, 2002 to Gerard A. Alphonse; U.S. Pat. No. 6,363,188 issued Mar. 26, 2002 to Gerard A. Alphonse; U.S. Pat. No. 6,417,524 issued Jul. 9, 2002 to Gerard A. Alphonse; U.S. Pat. No. 6,459,715 issued Oct. 1, 2002 to Viktor B. Khalfin, et al.; U.S. Pat. No. 6,556,611 issued Apr. 29, 2003 to Viktor B. Khalfin, et al.; U.S. Pat. No. 6,639,930 issued Oct. 28, 2003 to Giora Griffel, et al.; U.S. Pat. No. 6,669,379 issued Dec. 30, 2003 to Zbigniew Janosik, et al.; U.S. Pat. No. 6,688,783 issued Feb. 10, 2004 to Zbigniew Janosik, et al.; U.S. Pat. No. 6,744,548 issued Jun. 1, 2004 to Joseph H. Abeles; and U.S. Pat. No. 6,909,826 issued Jun. 21, 2005 to Yongming Cai, et al., all of which are incorporated herein by reference). However, conventional edge-emitting lasers must be cleaved before they are able to be tested, and assembly from individual lasers or linear strips of lasers into complex topologies is difficult and expensive. Further, these types of lasers have a high threshold level required to achieve lasing, requiring high power and generating excess heat, making them unsuitable for most applications requiring implanted devices in humans or other animals.
The present application is related to the following patents and applications, each of which is incorporated by reference: U.S. patent application Ser. No. 11/071,060 by Anita Mahadevan-Jansen et al. entitled “System and Methods for Optical Stimulation of Neural Tissues” filed Mar. 3, 2005; U.S. Pat. No. 6,310,083 by Joseph P. Y. Kao et al. issued Oct. 30, 2001, entitled “Caged amino acid derivatives bearing photolabile protective groups”; U.S. Pat. No. 5,430,175 to George P. Hess, et al. issued Jul. 4, 1995 titled “Caged carboxyl compounds and use thereof”
Various patents and patent applications have also described structures, materials and processes for making and using vertical-cavity surface-emitting lasers (VCSELs) (e.g., U.S. Patent Application Publication No. 2007-0036493A1 titled “Bidirectional optical fiber link systems components couplers,” U.S. Patent Application Publication No. 2003-0165171A1 titled “Temperature compensated lasers,” U.S. Patent Application Publication No. 2001-0021287A1 titled “Electro-opto-mechanical assembly for coupling a light source or receiver to an optical waveguide,” each of which is incorporated by reference). All of the following are incorporated by reference: U.S. Pat. No. 7,095,770 to Ralph H. Johnson titled “Vertical cavity surface emitting laser including indium, antimony and nitrogen in the active region” describes materials suitable for emitting laser light having wavelengths in the range of 1260 to 1650 nm. U.S. Pat. No. 5,754,578 to Jayaraman is titled “1250-1650 nm vertical cavity surface emitting laser pumped by a 700-1050 nm vertical cavity surface emitting laser.” U.S. Pat. No. 5,799,030 to Mary K. Brenner is titled “Semiconductor device with a laser and a photodetector in a common container.” U.S. Pat. No. 7,085,300 to Thomas R. Werner et al. is titled “Integral vertical cavity surface emitting laser and power monitor.” U.S. Pat. No. 6,542,530 to Chan-Long Shieh et al. titled “Electrically pumped long-wavelength VCSEL and methods of fabrication” describes materials and structures for electrically pumped, long-wavelength VCSEL includes a long wavelength active region. Because nitrogen, indium, and Sb all reduce the band gap energy, the achievable wavelengths extend to wavelengths longer than either 1310 nm used for datacom or 1550 nm used for telecom. U.S. Patent Application Publication No. 2006-0276861A1 by J. T. Lin titled “Non-invasive method and system for the treatment of snoring and nasal obstruction” describes a laser for thermal shrinkage of soft tissue of uvula, soft palate, nasal turbinate or tongue base for the treatment of snoring, nasal obstruction or sleep apnea are disclosed. The preferred laser includes infrared laser about 0.7 to 1.85 micron, pulse duration about 100 microsecond to 5 seconds, spot size of about 2 to 5 mm and power of about 2 to 20 W at the treated area. U.S. Pat. No. 5,484,432 to Bruce J. Sand titled “Collagen treatment apparatus” described thermal shrinkage of collagen tissue by irradiation with coherent energy in the wavelength band of 1.80 to 2.55 microns as generated by a laser.
United States Patent Application 20030236458 titled “Spectroscopic systems and methods for detecting tissue properties” by Hochman, Daryl W. is herein incorporated by reference. The application describes methods for optically detecting physiological properties in an area of interest by detecting changes in the intrinsic or extrinsic optical properties of tissue in the area of interest are disclosed. The present invention optically detects blood flow changes, blood characteristics and blood vessel abnormalities, as well as determining the presence and location of abnormal or pathological tissue for identifying and mapping the margins of abnormal tissue, such as tumor tissue during surgical or diagnostic procedures, and for grading and characterizing tumor tissue. The application also describes systems and methods for distinguishing neuronal tissue from surrounding tissue, for distinguishing functional neuronal tissue from dysfunctional tissue, and for imaging functional neuronal areas in the cortex. Methods and systems of the described in the application may be implemented using a contrast enhancing agent or by stimulation of activity.
U.S. Pat. No. 7,194,063 titled “Methods for implementing microbeam radiation therapy” to Dilmanian; F. Avraham et al. is herein incorporated by reference. The patent describes a method of performing radiation therapy that includes delivering a therapeutic dose such as X-ray only to a target (e.g., tumor) with continuous broad beam (or in-effect continuous) using arrays of parallel planes of radiation (microbeams/microplanar beams). Microbeams spare normal tissues, and when interlaced at a tumor, form a broad-beam for tumor ablation. Bidirectional interlaced microbeam radiation therapy (BIMRT) uses two orthogonal arrays with inter-beam spacing equal to beam thickness. Multidirectional interlaced MRT (MIMRT) includes irradiations of arrays from several angles, which interleave at the target. Contrast agents, such as tungsten and gold, are administered to preferentially increase the target dose relative to the dose in normal tissue. Lighter elements, such as iodine and gadolinium, are used as scattering agents in conjunction with non-interleaving geometries of array(s) (e.g., unidirectional or cross-fired (intersecting) to generate a broad beam effect only within the target by preferentially increasing the valley dose within the tumor.
U.S. Pat. No. 7,003,353 titled “Photovoltaic powered charging apparatus for implanted rechargeable batteries” to Leon Parkhouse is herein incorporated by reference. The patent describes a photovoltaic powered charging unit that is mounted in a head covering, such as a cap or hat, for a patient who has an inductively chargeable medical device implanted in his head. The implanted device includes an implanted battery which powers the device. The photovoltaic cells provide continuous charging for the implanted battery and power for the implanted device when subjected to light. The charging unit includes a nonphotovoltaic cell that may be used to charge the implanted battery and power the implanted device in the absence of sufficient power from the photovoltaic cells. The cap has a sending coil located so that when the wearer dons the cap, the sending coil aligns with a receiving coil implanted in the patient's skull or brain. The implanted receiving coil is coupled to provide charging current to the implanted battery and power to the implanted device.
United States Patent Application 20080183247 titled, “Radio frequency transponder based implantable medical system” by Harding, William C. is herein incorporated by reference. This application describes an implantable medical device (IMD) system that includes an IMD, a transceiver antenna lead for the IMD, and a wireless therapy delivery transponder or probe that is remotely activated by the IMD via the transceiver antenna lead. The IMD and the wireless probe communicate using wireless RF-based transponder techniques. The wireless probe includes a capacitor that is charged when the IMD emits an appropriate electromagnetic field from the transceiver antenna lead. The wireless probe delivers electrical therapy in the form of electrical pulses from the capacitor in response to RF activation signals emitted by the IMD via the transceiver antenna lead.
U.S. Pat. No. 6,823,109 titled, “Optical fiber-lens array” to Sasaki, Yasuji et al. is herein incorporated by reference. This patent describes an optical fiber-lens array, wherein the optical axes of the gradient index rod lens and of the optical fiber are aligned easily with high accuracy. The optical fiber-lens array includes a first substrate having a gradient index rod lens accommodated in V-shaped grooves for rod lenses formed in parallel at prescribed pitches, and a second substrate having optical fibers accommodated in V-shaped grooves for optical fibers formed at the same array pitches with said V-shaped grooves for rod lenses. The first substrate and the second substrate are connected by guide pins placed on the common positioning guide grooves formed on the first substrate and the second substrate with the respective end surfaces of the gradient index rod lenses and the respective end surfaces of the corresponding optical fibers faced toward each other.
Background on Neural Stimulation
Neural prosthetic devices are artificial extensions to the body that restore or supplement nervous-system function that was lost during disease or injury. The devices stimulate remaining neural tissue, providing some input to the nervous system through multiple independent channels that work in parallel to provide an overall effect within the body. Heretofore, the challenge for neural prostheses is to stimulate neurons selectively with individual channels. However, the electrical current spreads widely in the tissue and does not allow easily stimulating small neuron populations. This limitation is based on fundamental physical principles of electrical stimulation that even the best electrode design has not yet overcome.
Researchers have therefore shifted their focus toward improving electrodes and stimulation paradigms. Recent animal experiments have caused a fundamental paradigm shift in the field of neural stimulation, namely the use of light rather than electrical energy to induce nerve potentials. In particular, Aculight Corporation has previously developed a novel infrared neuro-stimulator that uses light to activate neurons. The advantage of the novel device over existing contemporary devices includes its non-invasive character of stimulating the nerve and the possibility of focusing the stimulus to extremely small populations of neurons allowing for spatial stimulation that mimics better the natural stimulation of the neurons. The technology will not only serve the hearing impaired but will help to define the laser parameters necessary to develop any other neural prostheses that require fast repetition rates of stimulation, including vestibular or possible retinal prostheses. For light stimulation to be practical in an implant, a technology must be used that is compact, power efficient, and consists of an array of lasers with the capability of electronic control of individual channels.
What are needed are improved methods and apparatus for stimulation of bodily tissues (such as stimulating one or more nerves together or separately) using light (such as infrared laser light from an array of lasers).